They've slept in cars and on couches, used park bathrooms to bathe and attempted to move to other cities for work. For the past six months, Yesenia and Christopher Ramirez, their 3-year-old daughter, Emily, and their 18-month-old son, Joshua, have lived in a tiny room at a Tenderloin shelter run by Hamilton Family Center.

In August, they won the lottery. But in San Francisco's housing market, winning the lottery isn't always enough - even when homeless families are given the chance at a permanent space, debt and other past economic decisions can come back to haunt them, making it difficult for city officials and nonprofits to help. And in the current rental market, the problem could get worse.

The Ramirezes were one of 38 households randomly chosen to rent a below-market-rate unit at NEMA, a 754-unit luxury condominium development in the burgeoning Mid-Market neighborhood. Just steps from Twitter's offices, the sleek, two-tower development, marketed as "tech-savvy and design-driven," is worlds away from the sparse room the family has called home since June.

Soon after, Christopher Ramirez got a job as a dishwasher, and the family thought they'd be able to afford the discounted $1,066 rent and move into NEMA by Christmas. But in October, the Ramirezes were notified that they were 29 points short of the building's minimum credit score and the unit would go to someone else.